Submission #996565

#	Time	Username	Problem	Language	Result	Execution time	Memory
996565		makrav	JJOOII 2 (JOI20_ho_t2)	C++14	100 / 100	11 ms	2660 KiB

ho_t2

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;

#define all(a) (a).begin(), (a).end()
#define sz(a) (int) a.size()
#define pb push_back
#define ff first
#define sc second
#define pii pair<int, int>
#define f(i, l, r) for (int i = (l); i < (r); i++)
#define double ld

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, k; 
    cin >> n >> k;
    string s; cin >> s;
    vector<int> posj, posi, pref(n + 1);
    for (int i = 0; i < n; i++) {
        pref[i + 1] = pref[i];
        if (s[i] == 'J') posj.push_back(i);
        else if (s[i] == 'I') posi.push_back(i);
        else {
            pref[i + 1]++;
        }
    }
    int ans = 1e9;
    int ind = -1;
    for (int i = 0; i < n; i++) {
        if (s[i] == 'J' && ind+k<sz(posj)) {
            ind++;
            int L = -1, R = sz(posi);
            while (R - L > 1) {
                int M = (L + R) / 2;
                if (M < (k - 1) || posi[M - k + 1] < posj[ind+k-1]) {
                    L = M;
                    continue;
                }
                int cntt = pref[posi[M - k + 1]] - pref[posj[ind+k-1]];
                if (cntt>=k)R=M;
                else L=M;
            }
            if (R < sz(posi)) ans = min(ans, n - 3 * k - i - (n - posi[R] - 1));
        }
    }
    cout << (ans == 1e9 ? -1 : ans) << '\n';

    return 0;
}

• Subtask 1: 1 / 1
• Subtask 2: 12 / 12
• Subtask 3: 87 / 87